<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="css1.css"/>
</head>
<body>

<script type="text/javascript" src="../jquery_aaa.js"> </script>


<div id="div1" >
    <span id="span1">1</span>
</div>


<script type="text/javascript">

    $("#div1").on('click', function () {
        alert("div1...");
    });

    $("#span1").on('click', function () {
        alert("span1...");
        event.stopPropagation();
    });

</script>

</body>
</html>